Diet plays an important role in patient response to anti-programmed death-1 (PD-1) cancer immunotherapy, preliminary findings from a gut microbiome study involving 146 melanoma patients suggest.
Specifically, a high-fiber diet was associated with a more diverse gut microbiome and with improved response to anti-PD-1 therapy, whereas a diet high in sugar and processed meat was associated with fewer of the gut bacteria known to be associated with improved response, Christine Spencer, PhD, reported during a press conference highlighting data to be presented at the upcoming American Association for Cancer Research (AACR) annual meeting in Atlanta.
“We found that patients who reported eating high-fiber diets were about five times as likely to respond to anti-PD-1 checkpoint blockade immunotherapy (odds ratio vs. low-fiber diet, 5.3),” said, a research scientist at the Parker Institute for Cancer Immunotherapy.
Notably, more than 40% of patients reported taking probiotics, and those, surprisingly, were also associated with reduced gut microbiome diversity, she said.
For this study, Dr. Spencer and her colleagues at the University of Texas MD Anderson Cancer Center, Houston, analyzed prospectively collected fecal samples from 146 melanoma patients, and collected baseline diet information via the National Cancer Institute dietary screener questionnaire, as well as information about probiotic and antibiotic use, in a subset of 113 who were initiating therapy at MD Anderson. Those patients were then followed to assess therapy response.
“Our early data suggest that different foods and supplements may impact response to cancer immunotherapy in patients, and we think this is likely mediated by the gut microbiome,” she said.
Since only 20%-30% of cancer patients respond to immunotherapy, the findings hint at potential approaches for improving gut microbiome diversity, and thus response to anti-PD-1 cancer immunotherapy.
“Eat your high-fiber foods: fruits, vegetables, and whole grains – lots of different kinds and lots of them,” she said. “High-fiber diets have been linked to health benefits in several other contexts, and this study, although preliminary, shows fiber is linked to more favorable gut microbiome in patients, and better response to cancer immunotherapy.”
Conversations about the use of probiotic supplements also are important, she said.
“A lot of people have the perception that probiotics will provide health benefits, but that might not be the case in cancer patients. We’re not saying all of them are bad, but the message is that these factors have never before been studied in patients on immunotherapy, and our data suggest for the first time that they could matter,” she said, noting that future directions include validation of the findings in larger cohorts.